Quantification of cyclooxygenase-2 methylation in gastric mucosa by denaturing high performance liquid chromatography assay / 中华预防医学杂志

<p><b>OBJECTIVE</b>To setup a quantitative assay for detection of cyclooxygenase-2 (COX-2) methylation in human gastric mucosa samples.</p><p><b>METHODS</b>A standard analysis system was established by denaturing high performance liquid chromatography (DHPLC) under the condition of 55 degrees C oven temperature and a linear acetonitrile gradient (4.0/min). While, a total of 10 cases of gastric biopsy samples were detected for methylation status of COX-2.</p><p><b>RESULTS</b>The complete methylated human promyelocytic leukemia cells (HL-60) and unmethylated gastric cancer cell line (MGC803) were used as positive and negative control. The proportion of the methylated copies of COX-2 was calculated according to the peak heights of methylated (M) and unmethylated (U) COX-2 in same PCR amplicon. The formula was Y = 1.0608 x M/(M + U), R(2) = 0.9894. Among 10 biopsy samples, the proportions of methylated copies of COX-2 in 2 cases of dysplasia were higher than superficial gastritis and chronic atrophy gastritis (24.5%, 18.4% vs 7.6%, 9.6%).</p><p><b>CONCLUSION</b>The methylation of COX-2 promoter CpG islands can be detected in human gastric mucosa samples by quantitative DHPLC assay, which could be used in the population-based study of precancerous gastric lesions.</p>

Association between promoter methylation of cyclooxygenase-2 and expression, and precancerous gastric lesions in a high-risk population / 中华预防医学杂志

<p><b>OBJECTIVE</b>To evaluate the relationship between cyclooxygenase-2 (COX-2) methylation and expression, and precancerous gastric lesions.</p><p><b>METHODS</b>Methylation status of COX-2 was evaluated by quantitative denaturing high performance liquid chromatography (DHPLC) in 1201 subjects with different gastric lesions. COX-2 expression was assessed by immunohistochemistry and Helicobacter pylori (H pylori) infection status was determined by 13C-urea breath test (13 C-UBT).</p><p><b>RESULTS</b>The percent of COX-2 methylation was increased steadily with the severity of gastric lesions, showing 10.6% of which with superficial gastritis/chronic atrophic gastritis (SG/CAG), 11.8% with intestinal metaplasia (IM) and 13.8% with indefinite dysplasia/dysplasia (Ind DYS/DYS) (chi2 = 8.312, P = 0.016). Stratified analysis indicated that the percents of COX-2 methylation in subjects with H pylori negative still increased with the severity of gastric lesions,of 8.8% in SG/CAG, 10.6% in IM and 14.1% in Ind DYS/DYS (chi2 = 6.629, P= 0.036). Moreover,the methylated proportion of COX-2 was negatively associated with the expression in gastric lesions, from 13.3% with mild expression to 7.6% with strong expression (chi2 = 10.400, P = 0.015).</p><p><b>CONCLUSION</b>Our findings indicated that COX-2 methylation was significantly associated with precancerous gastric lesions and H pylori infection, suggesting that promoter methylation of COX-2 might play an important role in the progression of gastric lesions.</p>

The associations of serum gastrin level with Helicobacter pylori infection / 中华预防医学杂志

<p><b>OBJECTIVE</b>To investigate the associations of serum gastrin-17 (G-17) concentration with helicobacter pylori (Hp) infection.</p><p><b>METHODS</b>A (13)C-urea breath and ELISA test to determine the Helicobacter pylori status and to detect the serum gastrin concentration was conducted in 242 villagers in Linqu of Shandong Province, a high gastric cancer prevalence area in China.</p><p><b>RESULTS</b>Of 242 subjects, 65 of 111 were found Hp-positive in males (58.56%), compared with 65 of 131 in females (49.62%) (chi(2) = 1.932, P = 0.165). The statistical difference was not observed among different age groups (chi(2) = 4.185, P = 0.123). The average level of G-17 among 242 subjects was (24.43 +/- 25.46) pmol/L and it was statistically higher in females (29.87 +/- 28.18) pmol/L than that in males (18.01 +/- 20.11) pmol/L (Z = -3.618, P < 0.001). However, there was no statistical difference found among age groups (chi(2) = 1.948, P = 0.378). The G-17 level in Hp-negative group (35.50 +/- 30.92) pmol/L was observed significantly higher than in Hp-positive group (14.90 +/- 13.79) pmol/L (Z = 5.368, P = 0.0001).</p><p><b>CONCLUSION</b>The G-17 concentration was found higher in Hp-negative subjects than in Hp-positive subjects, and higher in female than in male, but no difference was found among age groups.</p>